1. Field of the Invention
The present invention relates to a recording apparatus that records an image on a recording medium by using a recording head for discharging ink, and to a control method of the recording apparatus.
2. Description of the Related Art
In inkjet recording apparatuses, increases in speed and image quality have been demanded. To meet the demand on the increase in image quality, a technique for adjusting a deviation of a dot-recording position (recording position), i.e., a recording-position deviation, is essential, in order to decrease image defect, such as unevenness or stripes of an image, which occurs depending on attachment accuracy of a recording head or which is caused by an assembly error of a recording apparatus.
Such a recording-position deviation may appear between a dot recorded by forward scanning and a dot recorded by backward scanning of the recording head, or between dots recorded by different nozzle arrays. Also, a deviation may appear when a dot recorded by an upstream nozzle group of a nozzle array is recorded at a position deviated from a dot recorded by a downstream nozzle group thereof in a main scanning direction of the recording head in a case where the recording head is attached to the recording apparatus in an inclined manner.
To adjust the recording-position deviation, it is necessary to record a plurality of patterns on a recording medium, to acquire an adjustment value from density information acquired from the patterns, and to obtain a deviation time, at which an ink droplet is discharged, based on the adjustment value. Meanwhile, to record the patterns for acquiring the adjustment value, the plurality of patterns are recorded while a position of a dot (adjustment dot) by a second recording operation is deviated relative to a position of a dot (reference dot) recorded by a first recording operation. For example, to adjust a deviation between a recording position by forward scanning and a recording position by backward scanning, a plurality of patterns are recorded such that a deviation of a position of a dot recorded by backward scanning is changed relative to a position of a dot recorded by forward scanning. Also, to adjust a recording-position deviation caused by inclination of the recording head, a reference dot is recorded by the upstream nozzle group, the recording medium is conveyed, and then an adjustment dot is recorded by the downstream nozzle group. At this time, a plurality of patterns are recorded while a relative deviation between the reference dot and the adjustment dot in the main scanning direction is changed. After the plurality of patterns are recorded, an optical sensor provided in the recording apparatus measures optical characteristics (for example, reflection optical densities) of the patterns to acquire information relating to the optical characteristics of the patterns and to acquire an adjustment value.
Japanese Patent Laid-Open No. 2005-88439 discloses a technique in which an optical sensor reads optical characteristics of a plurality of patterns, so that a deviation between recording positions is adjusted. In particular, the technique is to adjust the recording-position deviation by two operations of rough adjustment and fine adjustment. With this technique, the plurality of patterns are recorded by the rough adjustment and the fine adjustment. An adjustment value is roughly determined by the rough adjustment and then patterns for fine adjustment are recorded with smaller deviations. Thus, an amount of patterns to be recorded can be decreased.
To attain the increase in image quality, it is necessary to adjust various types of recording-position deviations. However, the amount of patterns is increased as the number of types (adjustment items) of the recording-position deviations to be adjusted is increased. Hence, a time required for adjustment and an area of a recording medium to be consumed are increased.
If the adjustment value is roughly determined by the rough adjustment and the plurality of patterns for the fine adjustment are recorded like the technique disclosed in Japanese Patent Laid-Open No. 2005-88439, the amount of patterns to be recorded can be decreased, and the time required for the adjustment and the area of a recording medium to be consumed can be decreased. However, with this technique, a plurality of patterns have to be recorded for each of the rough adjustment and fine adjustment.